Projection system

Abstract

A projection system has an illumination apparatus, a converging lens array, an imaging apparatus, and a projection lens. The illumination apparatus has a light source, a light collecting element, and a rod integrator. The light collecting element has a frustum shape, and connects to the rod integrator at an end with a smaller surface area. Another end of the light collecting element with a larger surface area faces the light source. The light beam from the light source enters the light collecting element and is reflected by the light collecting element into the rod integrator. The rod integrator homogenizes the light beam and reflects the light beam to the imaging apparatus, which transforms the light beam into an image beam and displays an image to a surface through the projection lens.

1 . A projection system comprising:
 an illumination apparatus comprising:
 a light source for providing a convergent light beam; 
 a rod integrator having an incident end and an exit end and receiving the convergent light beam focused at the incident end of the rod integrator through the incident end of the rod integrator and letting the convergent light beam leave through the exit end of the rod integrator; 
 a light collecting element disposed between the light source and the rod integrator and positioned on a light path of the convergent light beam, the light collecting element having a first end facing the rod integrator, a second end facing the light source, and at least one side connected between the first end and the second end, the light collecting element shrinking from the second end to the first end, the side of the light collecting element having at least one reflective surface for reflecting a portion of the light beam entering the light collecting element to the incident end of the rod integrator; and 
 a converging lens array for scaling the light beam exiting from the exit end of the rod integrator; 
   an imaging apparatus for receiving the light beam scaled by the converging lens array and forming an image; and   a projection lens for projecting the image to a surface.   
   
   
       2 . The projection system of  claim 1 , wherein a surface area of the second end of the light collecting element is greater than a surface area of the first end, and the side slants from the second end to the first end. 
   
   
       3 . The projection system of  claim 1 , wherein a cross-section of the first end and a cross-section of the second end of the light collecting element are rectangular, semi-circular, circular, or octagonal. 
   
   
       4 . The projection system of  claim 1 , wherein the light collecting element is hollow, and the reflective surface is formed by plating an interior surface of the side of the light collecting element with a reflective material. 
   
   
       5 . The projection system of  claim 1 , wherein the light collecting element is solid, and the reflective surface is formed by plating the side with a reflective material. 
   
   
       6 . The projection system of  claim 1 , wherein the imaging apparatus is a digital micromirror device (DMD). 
   
   
       7 . The projection system of  claim 1  further comprising a color wheel disposed between the light collecting element and the rod integrator. 
   
   
       8 . The projection system of  claim 1  further comprising a polarizing transformation unit disposed between the light collecting element and the rod integrator, the polarizing transformation unit comprising a polarization beam splitter and a half-wave plate. 
   
   
       9 . The projection system of  claim 1 , wherein the light source comprises an elliptical reflector and a light source disposed within the elliptical reflector. 
   
   
       10 . The projection system of  claim 1 , wherein the light source comprises a parabolic reflector, a light source disposed within the parabolic reflector, and a condenser lens. 
   
   
       11 . The projection system of  claim 1 , wherein the rod integrator is a columnar rod integrator or a frustum rod integrator. 
   
   
       12 . The projection system of  claim 1 , wherein the first end of the light collecting element is directly connected to the incident end of the rod integrator, and a surface area of the first end is equal to a surface area of the incident end. 
   
   
       13 . The projection system of  claim 1 , wherein the incident end of the rod integrator includes a reflective surface, the reflective surface defining an aperture facing the first end of the light collecting element. 
   
   
       14 . The projection system of  claim 13 , wherein the reflective surface comprises aluminum plated onto the internal side of the reflective surface. 
   
   
       15 . A projection system comprising:
 an illumination apparatus comprising:
 a light source for providing a parallel light beam; 
 a lens array; 
 a plurality of light collecting elements disposed at a side of the lens array away from the light source, the light collecting elements arranged in an array corresponding to the lens array, the each light collecting element having a second end facing the light source, a first end corresponding to the second end, and at least one side connected between the first end and the second end, the each light collecting element shrinking from the second end to the first end, the side of the light collecting element having at least one reflective surface for reflecting a portion of the light beam entering the light collecting element; and 
 a converging lens array for scaling the light beam exiting the light collecting element; 
   an imaging apparatus for receiving the light beam scaled by the converging lens array and forming an image; and   a projection lens for projecting the image to a surface.   
   
   
       16 . The projection system of  claim 15 , wherein the imaging apparatus is a liquid crystal display (LCD) panel. 
   
   
       17 . The projection system of  claim 16  further comprising a polarizing transformation element disposed at an end of the light collecting elements away from the light source, the polarizing transformation element comprising a plurality of polarization beam splitters and a plurality of half-wave plates. 
   
   
       18 . The projection system of  claim 1 , wherein the incident end of the rod integrator includes a reflective surface, the reflective surface defining an aperture facing the first end of the light collecting element. 
   
   
       19 . The projection system of  claim 18 , wherein the reflective surface comprises aluminum plated onto the internal side of the reflective surface.